High memory usage

[Hanna Ruotsalainen]

Hi

I recently (about 2 weeks ago) moved over my users over to a new version 
of dovecot (2.0.9) and now the memory usage on the new server seems much 
higher than it was before.
The new server is a CentOS 6 VM with 4 GB of RAM and 4 CPUs and 
according to top, it's used up all of the RAM and all of the Swap. 
Here's a sample of the output from top (sorted by allocated memory).

top - 10:42:36 up 22 days, 21:57, 1 user,  load average: 1.04, 1.40, 1.52
Tasks: 1643 total,   1 running, 1642 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.7%us,  0.7%sy,  0.0%ni, 93.3%id,  5.1%wa,  0.0%hi,  0.1%si,  
0.0%st
Mem:   3924432k total,  3779236k used,   145196k free,    23740k buffers
Swap:  4063228k total,  3181164k used,   882064k free,   156420k cached

   PID USER      PR  NI  VIRT  RES SHR S %CPU %MEM    TIME+  COMMAND
16738 root      20   0  399m 182m 436 S  0.0  4.8   5:50.58 config
18790 dovenull  20   0 54528  11m 2036 S  0.0  0.3   0:00.05 imap-login
22277 dovenull  20   0 54528  11m 2156 S  0.0  0.3   0:00.04 imap-login
22796 dovenull  20   0 54528  11m 2140 S  0.0  0.3   0:00.03 imap-login
22749 dovenull  20   0 54528  11m 2148 S  0.0  0.3   0:00.03 imap-login
22825 dovenull  20   0 54528  11m 2156 S  0.0  0.3   0:00.03 imap-login

This is with 1015 imap processes and 484 imap-login processes.
The old version was 1.0.rc15 and running on a CentOS 4 box with 2GB of 
RAM. It was overloaded but the RAM usage wasn't maxed out like this one 
is (not much swap usage and a large amount of cached memory).

Is this amount of memory usage normal? What could be causing it, if it 
isn't?

Thanks for your help,

Hanna

Here is the output of dovecot -n:

# 2.0.9: /etc/dovecot/dovecot.conf
# OS: Linux 2.6.32-431.29.2.el6.x86_64 x86_64 CentOS release 6.5 (Final) nfs
auth_verbose = yes
disable_plaintext_auth = no
listen = *
login_greeting = Ready.
mail_debug = yes
mail_location = 
maildir:/mail/%1Lu/%u:INDEX=/var/cache/dovecot/indexes/%1Lu/%u
mail_plugins = " mail_log notify"
maildir_very_dirty_syncs = yes
mbox_lazy_writes = no
namespace {
   inbox = yes
   location =
   prefix =
   separator = /
   type = private
}
passdb {
   args = /etc/dovecot/dovecot-ldap-pass.conf
   driver = ldap
}
plugin {
   mail_log_events = delete undelete expunge copy mailbox_delete 
mailbox_rename
   mail_log_fields = uid box msgid size
}
protocols = imap pop3
service anvil {
   client_limit = 1250
}
service auth {
   client_limit = 4300
   user = root
}
service imap-login {
   process_limit = 600
   service_count = 1
}
service imap {
   process_limit = 1536
}
service pop3-login {
   process_limit = 600
   service_count = 1
}
service pop3 {
   process_limit = 1536
}
ssl_ca = </etc/pki/tls/certs/ca-bundle.crt
ssl_cert = </etc/pki/dovecot/certs/dovecot.pem
ssl_key = </etc/pki/dovecot/private/dovecot.pem
userdb {
   args = /etc/dovecot/dovecot-ldap-user.conf
   driver = ldap
}
version_ignore = yes
protocol imap {
   mail_max_userip_connections = 10
   ssl_cert = </etc/pki/dovecot/certs/imap.ecuad.ca.pem
   ssl_key = </etc/pki/dovecot/private/imap.ecuad.ca.pem
}
protocol pop3 {
   pop3_uidl_format = %08Xv%08Xu
   ssl_cert = </etc/pki/dovecot/certs/pop.ecuad.ca.pem
   ssl_key = </etc/pki/dovecot/private/pop.ecuad.ca.pem
}
protocol lda {
   postmaster_address = _postmaster at example.com_
}

-- 

Hanna Ruotsalainen Coordinator of Information Applications, IT Services 
| tel 604 844 3875 local 3875

emily carr university of art + design <http://www.ecuad.ca> |  1399 
Johnston Street, Vancouver  BC  V6H 3R9